A touch panel having a displaying function which is incorporated in an electronic apparatus such as a cellular phone, a smart phone, or a PDA is mounted through the following method. That is, as illustrated in FIG. 16, a display unit 102 such as a liquid crystal display is fitted into a lower casing 101, then a touch panel 103 is attached to the display unit 102 at the peripheries of their surfaces or over their entire surfaces, thereafter the touch panel 103 is covered with an upper casing 104 having an opening portion 104a which defines the display area of the touch panel 103 while the periphery of the surface of the touch panel 103 is pressed by the upper casing 104 and, then, the upper casing 104 and the lower casing 101 are coupled to each other to mount the touch panel 103 thereto (refer to patent document 1, (JP-A No. 2000-270063), for example).
However, the background art has issues as follows.
Since the touch panel 103 is covered with the upper casing 104 at the periphery of the surface of the touch panel 103, there is inevitably generated a level difference corresponding to the thickness of the upper casing 104 with respect to the surface of the touch panel 103, which makes it difficult to provide a structure of good design having a flat surface.
Furthermore, when the upper casing 104 is mistakenly pressed during input operations, the touch panel 103 may be pressed on a portion of the peripheral portion by the upper casing 104 thereby causing false input to the touch panel 103 or the touch panel 103 may be caused to slide repeatedly at the same portion thereof along the edge of the opening portion 104a of the upper casing 104 by being guided by the level difference in the upper casing 104, thereby causing degradation of the touch-inputting function of the touch panel 103. Furthermore, when the operation surface of the touch panel 103 is wiped for removing dirt such as oils adhered thereto through inputting and the like, it is difficult to wipe completely the operation surface near the opening portion 104a of the upper casing 104.
Further, when a design sheet having a frame pattern at the periphery of the operation surface of the touch panel 103 within the opening portion 104a of the upper casing 104 or having characters describing a brand name or a model name printed thereon is attached in order to improve the design of the electronic apparatus, the sizes of the effective display area of the display and the effective input area of the touch panel 103 have to be reduced.
Furthermore, foreign substances such as dusts clog the gap between the upper casing and the touch panel, thereby inducing malfunction.